Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . d (Echinaster sanguino-lentus), undergoes the followingphases (fig. 371). § 558. If the eggs are ex-amined by the microscope, eachone is found to contain a small,pear-shaped body, which is theembryo (e), surrounded by atransparent envelope. On es-caping from the egg the littleanimal has an oblong form, witha constriction at the base ; this constriction, becoming deeperand deeper, forms a pedicle, (p\ which soon divides intothree lobes. Th
Outlines of comparative physiology touching the structure and development of the races of animals, living and extinct : for the use of schools and colleges . d (Echinaster sanguino-lentus), undergoes the followingphases (fig. 371). § 558. If the eggs are ex-amined by the microscope, eachone is found to contain a small,pear-shaped body, which is theembryo (e), surrounded by atransparent envelope. On es-caping from the egg the littleanimal has an oblong form, witha constriction at the base ; this constriction, becoming deeperand deeper, forms a pedicle, (p\ which soon divides intothree lobes. The disc also assumes a pentagonal form, withfive double series of vesicles ; the first rudiments of the rays,are seen to form in the interior of the pentagon. At the sametime the peduncle contracts still more, being at last entirelyabsorbed into the cavity of the body, and the animal soonacquires its final form (m). § 559. Analogous transformations take place in the Coma-tula. In early life it is fixed to the ground by a stem (), but becomes detached at a certain epoch, and then floatsfreely in the sea (fig. 373). On the other hand, the polypi. METAMORPHOSES OF ANIMALS. 357 Fig. 372.
Size: 1594px × 1567px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectzoology, bookyear1870
